1. Field of the Invention
The present invention relates to an image forming apparatus, such as a printer, a copier, a facsimile machine, etc.
2. Discussion of the Background Art
Recently, for the purpose of conserving the global environment, it is demanded that natural resources are saved and CO2 outputs are reduced. Companies can play a large role in meeting such a demand, because they can greatly contribute to conservation of the global environment by recycling their products and saving natural resources.
In a field of office equipment, replacement is frequent and lease contracts of printers and/or copiers are short. However, at present almost all of parts collected by the manufacturers are discarded and not recycled. Part of the reason is that, technical innovation is rapid and new products often include significantly different structures from previous products even one generation old. Thus, for example, a casing or an image formation unit or the like cannot be reused, presently. To increase efficiency of information transmission or to enrich visual effectiveness, a monochrome instrument is sometimes replaced with a color instrument. Conversely, to save cost, a color instrument is sometimes replaced with a monochrome instrument.
However, due to structural differences, even the same casing or the image formation unit or the like is hardly used in a new product. In general, the monochrome instrument more quickly forms images and is more productive than the color instrument. Thus, it is more natural that a new monochrome instrument is provided without recycling the color instrument.
In Japanese Patent Application Laid Open Nos. 2003-66685 and 2003-66686 (JP-2003-66685-A, JP-2003-66686-A), a method of recycling an intermediate transfer tandem type color image forming apparatus as a monochrome instrument is discussed. Specifically, a color image forming apparatus includes a black color (B) image formation unit having a B-color image bearer for carrying a B-color toner image, a yellow color (Y) image formation unit having a Y-color image bearer for carrying a Y-color toner image, a magenta color (M) image formation unit having a M color image bearer for carrying a M color toner image, and a cyan yellow color (C) image formation unit having a C color image bearer for carrying a C color toner image, each horizontally arranged side by side.
Below the above-mentioned image formation units, an intermediate transfer unit including an intermediate transfer belt is arranged. The intermediate transfer belt is tightly stretched and rotated by three supporting rollers, and contacted by each of the above-mentioned image formation units along a stretching region between first and second supporting rollers. As shown there, the image formation units of Y, M, C, and B colors are arranged in the intermediate transfer belt moving direction in this order. Further, Japanese Patent Application Laid Open No. 2003-66686 describes plural image formation units of C, M, B, and Y colors arranged in an intermediate transfer belt moving direction in this order.
When a color instrument is recycled as a monochrome instrument, the image formation units of Y, M, and C serving as second image formation units are generally detached. The intermediate transfer unit is also detached from the apparatus, and an intermediate transfer belt for the monochrome instrument is attached below the B-color image formation unit serving as a first image formation unit. The intermediate transfer belt of the monochrome instrument is tightly stretched and rotated by three supporting rollers. Specifically, the intermediate transfer unit of the monochrome instrument is attached so that a stretching region between the first and second supporting rollers of the intermediate transfer belt is contacted by an image bearer of B color. As a result, a distance from a contact position (i.e., a primary transfer position) between the intermediate transfer belt of B color and the image bearer to the supporting roller (of the belt conveyance) arranged downstream is shorter in the intermediate transfer unit of the monochrome instrument than in that of the color instrument. Thus, a length of the intermediate transfer belt of B color from the first to section transfer positions decreases, and accordingly, a first printing out time is shorter in the monochrome instruments recycled from the color instruments.
However, in these conventional image forming apparatuses, three toner container sections storing Y, M, and C color toner, respectively, and color use toner supply units serving as second toner supply units are provided to supply the color use toner to the image formation units of Y, M, and C colors, respectively. Separately, a toner container section storing black toner, and a black use toner supply unit serving as a first toner supply unit are also provided to supply the black toner to the image formation unit of B color.
The problem with this arrangement is that when the color instrument is recycled as the monochrome instrument, the color use toner supply units are detached from the apparatus and discarded together with color use image formation units. As a result, saving of the resources and recycling of the products are insufficient.